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<article class="post-warp" itemscope itemtype="http://schema.org/Article">
    <header class="post-header">
        <h1 class="post-title" itemprop="name headline">Shell 循环</h1>
        <div class="post-meta">
                Written by <a itemprop="name" href="http://blog.mr-wei.cn" rel="author">Mr.wei</a> with ♥ 
                <span class="post-time">
                on <time datetime=2019-09-03 itemprop="datePublished">September 3, 2019</time>
                </span>
                in
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    <div class="post-content">
        

        

        
        
     
          
          
          

          
          
          

          

<h2 id="while循环">while循环</h2>

<pre><code class="language-shell">while 表达式
do
	命令表
done
</code></pre>

<!-- more -->

<h3 id="示例">示例</h3>

<pre><code class="language-shell">#!/bin/bash
i=1
while [ $i -le 10 ]
do
	echo &quot;第$i次循环输出: $i&quot;
	i=$(($i+1))
done
</code></pre>

<h2 id="for循环">for循环</h2>

<pre><code class="language-shell">for 变量 in 列表
do
	命令表
done
</code></pre>

<ul>
<li>列表通常是由一些列以空格分隔的字符组成</li>
<li>循环在取完列表中的所有参数时停止</li>
<li>in 列表可以省略，如果省略则for将 脚本的位置参数作为列表</li>
</ul>

<h3 id="示例-1">示例</h3>

<pre><code class="language-shell">#!/bin/bash
for i in 1 2 3 4 5
do
	RESULT=`expr $i \* $i`
	echo &quot;$i ----------$RESULT&quot;
done
</code></pre>

<h2 id="until循环">until循环</h2>

<pre><code class="language-shell">until
	命令表1
test 表达式
do
	命令表2
done
</code></pre>

<ul>
<li>命令表1在循环开始前执行，且在每一次循环结束后再次执行</li>
<li>表达式为循环控制条件，在表达式为真时结束循环，表达式为假时继续执行循环</li>
</ul>

<h3 id="示例-2">示例</h3>

<pre><code class="language-shell">#!/bin/bash
i=1
echo -n &quot;请输入N的值：&quot;
read N
until 
test $i -gt $N
do
	RESULT=`expr $i \* $i`
	echo &quot;$i----------$RESULT&quot;
	i=$(($i+1))
done
</code></pre>

<h1 id="参考资料">参考资料</h1>

<ul>
<li><font size=6>Linux命令行与shell脚本编程大全</font></li>
</ul>

    </div>

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                <span>Author:</span>
                <span>Mr.wei </span>
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                    <span>Link:</span>
                    <a href=http://blog.mr-wei.cn/2019/shell-%E5%BE%AA%E7%8E%AF/>http://blog.mr-wei.cn/2019/shell-%E5%BE%AA%E7%8E%AF/</span>
            </p>
            
             
            <p class="copyright-item lincese">
                本文采用<a rel="license" href="http://creativecommons.org/licenses/by-nc/4.0/" #target="_blank">知识共享署名-非商业性使用 4.0 国际许可协议</a>进行许可
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            <i class="iconfont icon-tag"></i>Tag(s): 
            
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                    #shell</a></span>
            
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